finally found the source of the smoke smell that has been leaking into my
apartment somehow...it's coming from a specific electrical outlet in the
living room - how do I seal that bad boy up so no air seems thru? I don't
need to use it, so that's not an issue. Thanks

I had that happen in an apartment years ago. I covered the plates
with black electrical tape. I had to put silicone sealant around
one of the wall plates to keep it from leaking between the plastic
and the drywall.
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I wouldn't seal the plate to the wall. Take the plate off, and seal
between the box and drywall, and seal the wire inlets (don't
electrocute yourself). Then put the plate back on.